Quantum dots delivered to cell nucleus with a nanoneedle

Researchers have developed a nanoneedle that releases quantum dots directly into the nucleus of a living cell when a small electrical charge is applied (Image: Min-Feng Yu)

We recently saw the potential for nanoneedles and quantum dots to treat skin cancer, however researchers at the University of Illinois have gone one step further. They have created a nanoneedle (an incredibly small needle) that allows them to peak into the nucleus of a cell. When subjected to an electrical charge, the needle injects quantum dots into the nucleus of a living cell. These quantum dots (nanoscale crystals with unique properties in terms of light emission) can be used to monitor microscopic processes and cellular conditions, aid the diagnosis of disease, and track genetic information from within the nucleus.

Researchers in the past have attempted to use dyes to track the activity of a nucleus, however these dyes were too sensitive to light and the results were deemed inconclusive. The use of quantum dots can solve this problem, as they maintain stability in light, and are easily tracked due to their fluorescence.

“Lots of people rely on quantum dots to monitor biological processes and gain information about the cellular environment. But getting quantum dots into a cell for advanced applications is a problem,” said professor Min-Feng Yu, a professor of mechanical science and engineering at Illinois.

Accessing the nucleus has always proven difficult as it is surrounded by a membrane designed to prevent other molecules within the cell from entering. “This technique allows us to physically access the internal environment inside a cell,” added Yu. “It’s almost like a surgical tool that allows us to ‘operate’ inside the cell.”

Yu and his team, including engineering professor Ning Wang and postdoctoral researcher Kyungsuk Yum, coated a nanoneedle with a very fine layer of gold to create a nanoscale electrode probe. They then inserted the quantum dot-filled needle into the nucleus, and with a small electrical charge the quantum dots were released. This technique provided a level of control not commonly achievable by other molecular delivery methods and allowed for a close observation of the quantum dots under a standard fluorescence microscope.

“Now we can use electrical potential to control the release of the molecules attached on the probe,” explained Yu. “We can insert the nanoneedle in a specific location and wait for a specific point in a biologic process, and then release the quantum dots. Previous techniques cannot do that.”

The application of a nanoneedle, being minute in size, is ideal as it has a minimal effect on cells and will rarely cause disruption. Yu hopes to further enhance the technique to see if he can safely inject DNA fragments, proteins and enzymes into the nucleus to study a range of cellular processes, leading to improved diagnosis and treatment.

A full report on the team’s study will appear in the October edition of the journal Small.

Researchers have developed a nanoneedle that releases quantum dots directly into the nucleus of a living cell when a small electrical charge is applied (Image: Min-Feng Yu)

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